In addition to direct ingestion of oil through preening and drinking, 

 petroleum may be transferred to birds in their food. Evidence indicates that 

 petroleum is taken up, and at least partially eliminated, by a variety of 

 invertebrates exposed to oil (Anderson 1975, Burns 1976, Corner et al . 1976, 

 Fossato and Canzonier 1976). Nothing is known about the dynamics of accumula- 

 tion and elimination of petroleum compounds by birds, however. After pre- 

 liminary studies at Patuxent with several species of snails, clams, and 

 crayfish, the crayfish (Proeambarus spp.) was chosen as a food source for 

 mallard ducks (Tarshis, personal communication). The crayfish will be exposed 

 to petroleum-contaminated water before being fed to the ducks. Southern 

 Louisiana crude containing ^C napthalene will be used in an effort to 

 establish the kinetics of oil transfer from water to invertebrate to duck. 



REPRODUCTION 



Aquatic birds nesting on the shore or in nearshore areas of oceans and 

 lakes may be subject to high concentrations of petroleum from chronic urban 

 and industrial runoff, oil tanker spills, and offshore drilling. Large numbers 

 of birds at colonial nesting sites may be affected by a single oil spill. 

 The low yearly reproductive potential of most marine birds means that recovery 

 from a disastrous nesting season would be slow. 



In addition to those birds that are killed by oil spills, many are pre- 

 sumably coated with sublethal amounts of petroleum. Gulls with oil spots on 

 their plumage have been observed for up to 4 weeks after a major oil spill. 

 Some of this oil may be transferred from the feathers and feet of incubating 

 birds to their eggs. The effects of external applications of oil on avian eggs 

 are not well known; however, previous studies and field observations indicate 

 that eggs contaminated by crude or processed oil seldom hatch (Gross 1950, 

 Rittinghaus 1956, Hartung 1965, Kopischke 1972, Birkhead et al . 1973). Egg- 

 oiling experiments performed at Patuxent have shown that external applications 

 of only microliter amounts of SLC, Kuwait crude oil, or No. 2 fuel oil were 

 sufficient to produce very high embryonic mortality in artificially incubated 

 mallard eggs (Albers 1976; Szaro and Albers, in preparation; and Szaro and Coon, 

 unpublished data) (Table 2). 



High mortality also occurred in artificially incubated common eider 

 [Somatevia mollissima) eggs treated with 20 yl of No. 2 fuel oil (Szaro and 

 Albers 1976). Embryonic mortality was thought to be caused by toxic compounds 

 in petroleum, rather than by interruption of normal gaseous exchange because 

 the area covered by the oil was small. Furthermore, eggs treated with propylene 

 glycol exhibited normal hatching success, and eggs treated with a mixture 

 of 9 or 10 aliphatic compounds found in petroleum had normal or near-normal 

 hatching success (Table 2). These results suggest that the toxic components 

 probably are aromatic hydrocarbons or nonhydrocarbons. Mallard eggs have 

 also been treated with external applications of SLC and No. 2 fuel oil at 

 various stages during the incubation period. The petroleum was most toxic 

 during the first 10 days of incubation (Albers, in preparation) (Table 3). 



63 



